1. Field of the Invention
The present invention relates to the field of analysis, identification and classification of vehicles or wheeled movable engines, and particularly when these latter move in the course of their normal use, and has for its object a device to detect particularly one or several wheels of a vehicle or a wheeled movable engine, as well as a process for the detection, analysis and classification of vehicles or engines using this device.
2. Discussion of the Related Art
There already exist at present different types of systems permitting identifying wheeled vehicles, among which can be cited particularly piezo-electric, resistive, optical, ultrasonic and hyperfrequency detectors, as well as devices with pneumatic tubes or again with electromagnetic loops.
This latter type of device of identification is now present in the form of a rectangular or two rectangular loops, of large sizes of the order of 1.5 m to 2 m (2 m being measured in the direction of the width of the highway), disposed on or in the roadway and permitting receiving a signal representative of the assembly of the body of the vehicle including the wheels detected during passage of this latter over the loop or loops. The shape of the received signal and, as the case may be, the offset between two signals received by two loops, disposed with a spacing between them in the direction of displacement of the vehicle, permit respectively determining the nature of the vehicle, whether it is light or heavy, as well as its speed of displacement. Such a device is particularly known from EP-A-0035960.
However, this known device does not permit a fine or exact identification of the detected vehicles permitting particularly their classification into the ten categories defined by the Organization of Cooperation and Economic Development (OCDE) or into the fourteen categories of the French System for the Collection of Data (SIREDO).
Thus, this device does not detect the number of axles of the vehicle and, to effect this detection, it is necessary to add to it a supplemental device of the pneumatic tube type or piezo-electric detector detecting the passage of the axles.
This results in a complex assembly requiring constant maintenance because of the presence of the mechanical type detectors, which are subject to high wear.
The present invention particularly has for its object to overcome the mentioned drawbacks.
To this end, it has for its object a device constituted by at least one electromagnetic loop positioned on the roadway or in the roadway and by a unit for the evaluation of the influence of the passage of a vehicle over said loop or loops, characterized in that the electromagnetic loop or loops, each comprised by one or several turns, have on the one hand a small dimension in the direction of displacement of the vehicles or the axis of the roadway, less than the diameter of the wheels of the vehicles to be identified, and, on the other hand, a preferably rectangular shape and/or an arrangement disposed perpendicularly to the axis of the roadway, the loop or loops being disposed at least on the one or two tracks along which rolling takes place on the roadway and sensitive, in a distinct and opposed manner, to the electromagnetic influences of the metallic masses of the body or chassis of the vehicles, on the one hand, and the metallic masses of the tires of the corresponding wheels, on the other hand.
The invention also relates to a process for the detection, analysis and classification of vehicles or wheeled engines using the mentioned device, characterized in that it consists in noting the electromagnetic influences, on the one hand, of the metallic masses of the body or chassis of a vehicle, on the other hand, the metallic masses of the tires of the wheels of said vehicle, in a distinct and opposed manner, by means of at least one electromagnetic loop, disposed on or in the roadway and having a small dimension in the direction of displacement of the vehicles or along the axis of the roadway, to produce a signal indicating the number and the position of the wheels, relative to each other and relative to the body or chassis of the vehicle, in identifying the precise nature of the analyzed vehicle and classifying this latter in the predetermined categories, based essentially on the number and longitudinal arrangement of the wheels or axles, and storing the recovered data for a definite interval to permit their ultimate use.